Japan has begun to discharge its first batch of treated radioactive water from its crippled Fukushima nuclear power plant into the ocean Thursday, according to Japanese media reports, despite concerns raised by neighboring countries and fishing groups in the region.

The controversial discharge came after the International Atomic Energy Agency (IAEA) gave final approval to the discharge last month, saying Japan’s release plan met international standards.

The Fukushima plant has stored more than 1.3 million tons of water through a custom purification system known as the Advanced Liquid Processing System (ALPS) since three reactors melted down after a powerful earthquake struck off the coast in March 2011.

The discharge of the first batch of the treated water into the Pacific Ocean began at around 1 p.m. Thursday, according to media reports, marking a major step in a process expected to take over 30 years.

The first batch of 7,800 tons of water is expected to take place over about 17 days. On Thursday alone, around 200 to 210 tons will be released into the ocean.

Tokyo Electric Power Co. (TEPCO), the plant’s operator, earlier said it plans to release 31,200 tons, or approximately 2.3 percent, of the treated water by the end of March.

In the wake of the meltdown incident, South Korea has banned all seafood imports from eight Japanese prefectures near Fukushima since 2013 due to concerns over their radiation levels.

Although the IAEA has said Japan’s plan for the water discharge would have negligible impact on the environment, neighboring countries, including South Korea and China, worry that the water could contaminate seafood.

Japanese fisheries groups have also voiced opposition to the planned water release, fearing that it could further erode the reputation of seafood from Fukushima and nearby areas.

The Japanese government and TEPCO have said the water discharge is an unavoidable step in the decommissioning process.

Source: Yonhap News Agency